1. Field of the Invention
The present invention relates to apparatus and methods for removal of heat from electronic devices. In particular, the present invention relates to a threaded heat dissipation device retention mechanism, and, most particularly, to such mechanisms used with refrigeration or liquid cooling systems.
2. State of the Art
Higher performance, lower cost, increased miniaturization of integrated circuit components, and greater packaging densities of integrated circuits are ongoing goals of the computer industry. As these goals are achieved, microelectronic dice become smaller. Accordingly, the density of power consumption of the integrated circuit components in the microelectronic die has increased, which, in turn, increases the average junction temperature of the microelectronic die. If the temperature of the microelectronic die becomes too high, the integrated circuits of the microelectronic die may be damaged or destroyed.
Various apparatus and techniques have been used and are presently being used for removing heat from microelectronic dice. One such heat dissipation technique involves the attachment of an integrated heat spreader to a microelectronic die. FIG. 10 illustrates an assembly 300 comprising a microelectronic die 302 (illustrated as a flip chip) physically and electrically attached to a substrate 304 (such as an interposer, a motherboard, or the like) by a plurality of solder balls 306 extending between pads 308 on an active surface 312 of the microelectronic die 302 and lands 314 on the substrate 304. To mechanically and physically reinforce the solder balls 306 connecting the microelectronic die pads 308 and the substrate lands 314, an underfill material 310 is disposed therebetween.
The assembly 300 further includes an integrated heat spreader 316 comprising a conductive plate 318 having at least one extension 322. The integrated heat spreader 316 is attached to a surface 324 of the substrate 304 by an adhesive layer 326 between the substrate surface 324 and the extensions 322. A back surface 332 of the microelectronic die 302 is in thermal contact with a first surface 328 of the integrated heat spreader conductive plate 318. A first thermal interface material 334 may be disposed between the microelectronic die back surface 332 and the integrated heat spreader conductive plate first surface 328 to enhance conductive heat transfer therebetween.
The integrated heat spreader 316 is usually constructed from a thermally conductive material, such as copper, copper alloys, aluminum, aluminum alloys, and the like. The heat generated by the microelectronic die 302 is drawn into the integrated heat spreader 316 by conductive heat transfer. It is, of course, understood that additional heat dissipation devices can be attached to a second surface 338 of the integrated heat spreader conductive plate 318. These additional heat dissipation devices may include heat slugs and high surface area (finned) heat sinks, and may further include fans attached thereto, as will be evident to those skilled in the art. However, with the increasing heat generation by microelectronic dice, such heat dissipation devices have become or will become insufficient for removing heat. Thus, heat exchangers, such as liquid cooling and refrigeration systems, have become or will become necessary. In particular, refrigeration systems look to be the most promising heat dissipation solution for most of the future processor applications, as they are able to provide very low thermal resistances.
As shown in FIG. 11, a heat exchanger 342 is placed in thermal contact with the integrated heat spreader conductive plate second surface 338. A heat transfer fluid (represented by arrows 352) flows into inlet 344, draws heat from the heat exchanger 342, and exits from outlet 346, wherein the heat is removed from the heat transfer fluid 352 by heat exchange in a remote location (not shown), as will be evident to those skilled in the art. A second thermal interface material 354 is disposed between the heat exchanger 342 and the integrated heat spreader conductive plate second surface 338. The heat exchanger 342 is held in place by a retention clip 356.
However, in such a configuration, the force of the retention clip 356 on the heat exchanger 342 and the thermal cycling of the microelectronic die 302 during operation may result in the second thermal interface material 354 being xe2x80x9cpumped outxe2x80x9d from between the heat exchanger 342 and the integrated heat spreader conductive plate second surface 338. The loss of the second thermal interface material 354 results in higher thermal resistances. This problem is particularly an issue when a phase-change material is used for the second thermal interface material 354.
Therefore, it would be advantageous to develop retention mechanisms for the attachment of refrigeration and liquid cooling systems to effectively remove heat from microelectronic dice.